This is just a dictionary password cracker, there is no way that its going to work, brute force is the worst way of cracking the password it may takes days to get the password if the password is a dictionary word. The md5 algorithm is in one of the .js file in the yahoo mail itself the tough thing is reversing the MD5 hash which is practically impossible although recent studies have theoritically reversed the MD5 hash, people you dont need to be afraid of this crack, i mean this crack was like 4 years old now. Socail Engineering is a better way to get someones password and it works if know where to dig information